Please help me to understand how to rebuild the native npm modules for Electron 1.6.2?

I used steps from https://electron.atom.io/docs/tutorial/quick-start to create a simple Electron application.
Then I installed ref package and loaded it in main.js.
ref package - it is the native package. I have to rebuild this package to have ability to use it in the Electron application.

Rebuild native packages using npm:
rem # Electron’s version.
set npm_config_target=1.6.2
rem # The architecture of Electron, can be ia32 or x64.
set npm_config_arch=x64
set npm_config_target_arch=x64
rem # Download headers for Electron.
rem set npm_config_disturl=https://atom.io/download/electron
rem # Tell node-pre-gyp that we are building for Electron.
set npm_config_runtime=electron
rem # Tell node-pre-gyp to build module from source code.
set npm_config_build_from_source=true
rem # Install all dependencies, and store cache to ~/.electron-gyp.
set HOME=%USERPROFILE.electron-gyp
npm install

I do not understand.
Electron 1.6.2 was released only 15 days ago.iojs.org/download/release/v1.6.2/iojs-v1.6.2.tar.gz was created 2 years ago - 23-Mar-2015.
Why does electron-rebuild use very old iojs-v1.6.2.tar.gz to rebuild the native npm package with new Electron 1.6.2?

Electron’s version.

export npm_config_target=1.2.3
…
The --target=1.2.3 is version of Electron.
…
electron-rebuild --help
Usage: electron-rebuild --version [version] --module-dir [path]
Options:
-v, --version The version of Electron to build against

Why does electron-builder/node-gyp uses version of Electron as version of Node?

Ok, now I understand that electron-rebuild really uses old iojs-v1.6.2.tar.gz to rebuild native packages for new Electron.
I can rebuild ref package for x64 architecture and use it in my Electron application.
cd .\node_modules\ref
"D:\tools\nodejs\node.exe" “C:\tmp\test\node_modules\node-gyp\bin\node-gyp.js” “rebuild” “–target=1.6.1” “–arch=x64” “–build-from-source” --nodedir=D:\tools\iojs-v1.6.1
And it works.

But when I try to rebuild ref package for 3b bit architecture and set --arch=ia32 then Electron cannot start and complains that “Error: %1 is not a valid Win32 application”.